title: Ultrastructural circadian variation of mast cells in the pinna of the mouse.
abstract: It has been found previously under the light microscope that there was a circadian variation in mast cell number in the pinna of mice. The mast cell number was increased at 18.00 h and decreased at 06.00 h. In the current study, 5 mice of each group were synchronized for 4 weeks with a standard lighting regimen (light: 06.00-20.00 h; dark: 20.00-06.00 h). Both pinnas of every mouse of each group were removed at 06.00, 12.00, 18.00 and 24.00 h, respectively. Under the electron microscope, it was observed that more degranulated mast cells were found at 06.00 h and more intact mast cells were visible at 18.00 h. It appeared that the mast cell numbers, decreased and increased under the light microscope, were due to mast cell degradation and regranulation. This finding suggests that a functional circadian variation exists in the mast cell under physiological conditions.
authors.affiliation: Department of Histology and Embryology, Shanxi Medical College, Taiyuan, People's Republic of China.
authors.forename: X J
authors.initials: XJ
authors.lastname: Chen
authors.forename: Z Y
authors.initials: ZY
authors.lastname: He
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D004431:Ear, External / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D008297:Male; D008407:Mast Cells / Q000473:pathology / Q000648:ultrastructure*; D051379:Mice; D008854:Microscopy, Electron